Vitamins and Minerals: How Much Should You Take?

Vitamins and Minerals: How Much Should You Take?

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How much of a vitamin or mineral supplement should you take? Are your daily multivitamins enough, or should you worry about vitamin deficiency? Could you already be taking too much? It can be hard to tell -- especially with so many nutritional terms, abbreviations, and numbers out there. Here’s what you need to know.

To help people better understand the minimum and maximum doses for supplements, the Institute of Medicine has established some guidelines.

• The RDA (Recommended Dietary Allowance) and the AI (Adequate Intake) are the amounts of a vitamin or mineral you need to stay healthy and avoid nutritional deficiencies. They are tailored to women, men, and specific age groups.
• The UL (Tolerable Upper Intake Level) is the maximum amount of daily vitamins and minerals that you can safely take without risking an overdose or serious side effects. For certain nutrients, the higher you go above the UL, the greater the chance of having problems.

Separate from the RDA and the UL, the FDA uses a different measurement of nutritional intake.

• The DV (Daily Value) is the only measurement you’ll find on food and supplement labels. That’s because space is limited, and there’s a need for one single reference number. That number is the amount of a vitamin or nutrient that a person should get for optimum health from a 2,000 calories-a-day diet. The DV is sometimes the same as the RDA and sometimes not.

Although the details may be different, just remember that the RDA and DV are both designed to help us get the nutrients we need to prevent disease and avoid problems caused by malnutrition.
But many people take higher doses of specific supplements in the hopes of gaining other health benefits, like added protection against or treatment of disease.
Is taking doses higher than the RDA or DV safe? For many vitamins and minerals, yes. In some cases, doctors even recommend it. Take vitamin D, for instance. The RDA of vitamin D for a 60-year-old is 600 international units (IU). But for bone health, the National Osteoporosis Foundation recommends 800-1,000 IU for that age group.

Table: RDAs and ULs for Vitamins and Minerals

The Institute of Medicine has determined upper limits for 24 nutrients. Here is a chart comparing the RDA and UL for all of them.

This table only applies to adults age 19 or older. It also does not apply to women who are pregnant or breastfeeding, because they have different nutritional requirements.

Anyone who is under 19, pregnant, or breastfeeding should check with a doctor before using supplements.

Vitamin or Mineral	Recommended Dietary Allowance (RDA) or Adequate Intake (AI) Nutrients with AIs are marked with an (*)	Upper Tolerable Limit (UL) The highest amount you can take without risk
Boron	Not determined.	20 mg/day
Calcium	Age 1-3: 700 mg/day Age 4-8: 1,000 mg/day Age 9-18: 1,300 mg/day Age 19-50: 1,000 mg/day Women age 51+: 1,200 mg/day Men age 71+: 1,200 mg/day	Age19-50: 2,500 mg/day  Age 51 and up:2,000 mg/day
Chloride	Age 19-50: 2,300 mg/day Age 50-70: 2,000 mg/day Age 70 and older: 1,800 mg/day	3,600 mg/day
Choline (Vitamin B complex)	Age 70 and older: 1,800 mg/day Women: 425 mg/day *	3,500 mg/day
Copper	900 micrograms/day	10,000 micrograms/day
Fluoride	Men: 4 mg/day * Women: 3 mg/day *	10 mg/day
Folic Acid (Folate)	400 micrograms/day	1,000 micrograms/day This applies only to synthetic folic acid in supplements or fortified foods. There is no upper limit for folic acid from natural sources.
Iodine	150 micrograms/day	1,100 micrograms/day
Iron	Men: 8 mg/day Women age 19-50: 18 mg/day Women age 51 and up: 8 mg/day	45 mg/day
Magnesium	Men age 19-30: 400 mg/day Men age 31 and up: 420 mg/day Women age 19-30: 310 mg/day Women age 31 and up: 320 mg/day	350 mg/day This applies only to magnesium in supplements or fortified foods. There is no upper limit for magnesium in food and water.
Manganese	Men: 2.3 mg/day * Women: 1.8 mg/day*	11 mg/day
Molybdenum	45 micrograms/day	2,000 micrograms/day
Nickel	Not determined	1.0 mg/day
Phosphorus	700 mg/day	Up to age 70: 4,000 mg/day Over age 70: 3,000 mg/day
Selenium	55 micrograms/day	400 micrograms/day
Sodium	Age 19-50: 1,500 mg/day Age 51-70: 1,300 mg/day Age 71 and up: 1,200 mg/day	2,300 mg/day
Vanadium	Not determined	1.8 mg/day
Vitamin A	Men: 3,000 IU/day Women: 2,310 IU/day	10,000 IU/day
Vitamin B3 (Niacin)	Men: 16 mg/day Women: 14 mg/day	35 mg/day This applies only to niacin in supplements or fortified foods. There is no upper limit for niacin in natural sources.
Vitamin B6	Men age 19-50: 1.3 mg/day  Men age 51 up:1.7 mg/day  Women age 19-50: 1.3 mg/day  Women age 51 up: 1.5 mg/day	100 mg/day
Vitamin C	Men: 90 mg/day Women: 75 mg/day	2,000 mg/day
Vitamin D (Calciferol)	Age 1-70: 15 micrograms/day (600 IU, or international units) * Age 70 and older: 20 micrograms/day (800 IU) *	100 micrograms/day (4,000 IU)
Vitamin E (alpha-tocopherol)	22.4 IU/day	1,500 IU/day This applies only to vitamin E in supplements or fortified foods. There is no upper limit for vitamin E from natural sources.
Zinc	Men: 11 mg/day Women: 8 mg/day	40 mg/day